Frank De Geeter

We retrospectively evaluated how accurately preoperative imaging localizes parathyroid adenoma in superior versus inferior parathyroids. Over 6 years, 104 patients with primary hyperparathyroidism underwent parathyroid surgery in a single centre. Of these, 103 underwent ultrasound, 97 [^99mTc]pertechnetate/MIBI SPECT/CT and 30 [¹⁸F]fluorocholine (FCH) PET/CT. One patient with a unilateral double adenoma was excluded from the analysis. Surgical findings with histopathologic confirmation of adenoma were used as the standard. Ultrasound misjudged 5 of 48 detected lower adenomas as upper, but 14 of 29 upper adenomas as lower (error rate 10 vs 48%, p = 0.0002). The corresponding error rates for [^99mTc]pertechnetate/MIBI SPECT/CT were 3 versus 55% (p = 0.000014), and for [¹⁸F]FCH PET/CT 17 versus 36% (p = 0.26). Our results suggest that about half of the superior parathyroid adenomas which are detected, are erroneously assigned to the inferior position by both ultrasound and SPECT/CT imaging whereas the opposite mistake is significantly less frequent with ultrasound and SPECT/CT.

Amyloidoisis in patients with Waldenstrom macroglobulinemia (WM) mostly involves the heart, peripheral nerves and kidneys. Retroperitoneal amyloidosis is a rare finding. We describe a 62-year-old man with an incidental finding of a monoclonal gammopathy and elevated inflammatory parameters. Bilateral moderately active retroperitoneal infiltration with punctiform calcifications was found on fluorine-18-fluorodeoxyglucose (F- 18-FDG) positron emission tomography/computed tomography (PET/CT) imaging. Taken together, these findings are suggestive of Waldenstrom associated amyloidosis. Computed tomography-guided retroperitoneal biopsy confirmed the diagnosis.

The objective of this study was to retrospectively evaluate preoperative imaging modalities for localization of parathyroid adenomas with a view to enable minimally invasive parathyroidectomy and in particular, to consider the contribution of ¹⁸F-fluorocholine-PET/CT. 104 patients with primary hyperparathyroidism, who underwent parathyroid surgery in a single centre during a 6-year period were included. Of these, 103 underwent ultrasound, 97 ^99mTc-Pertechnetate/SestaMIBI-SPECT, 20 MRI and 30 ¹⁸F-fluorocholine-PET/CT. Based on surgical findings, sensitivities and specificities for correct lateralisation in orthotopic locations were: for ultrasound 0.75 (0.65–0.83) and 0.89 (0.81–0.94), for ^99mTc-MIBI-SPECT 0.57 (0.46–0.67) and 0.97 (0.91–0.99), for MRI 0.60 (0.36–0.81) and 0.83 (0.59–0.96) and for ¹⁸F-fluorocholine-PET/CT 0.90 (0.73–0.98) and 0.90 (0.73–0.98). Correctly lateralized adenomas were significantly larger than those not found with ultrasound (p = 0.03) and SPECT (p = 0.002). Pre-operative PTH-levels were higher in single adenomas detected by scintigraphy than in those not (p = 0.02). 64 patients could be treated with a minimally invasive procedure. Cure after parathyroidectomy was obtained in 94% of patients. ¹⁸F-Fluorocholine-PET/CT could be shown to be a highly accurate modality to localize parathyroid adenomas preoperatively, obviating the need for total exploration in the majority of patients in whom ultrasound and scintigraphic results are discordant or both negative.

Background: Metal artefact reduction (MAR) techniques still are in limited use in positron emission tomography/computed tomography (PET/CT). This study aimed to investigate the effect of Smart MAR on quantitative PET analysis in the vicinity of hip prostheses. Materials and methods: Activities were measured on PET/CT images in 6 sources with tenfold activity concentration contrast to background, attached to the head, neck and the major trochanter of a human cadaveric femur, and in the same sources in similar locations after a hip prosthesis (titanium cup, ceramic head, chrome-cobalt stem) had been inserted into the femur. Measurements were compared between PET attenuation corrected using either conventional or MAR CT. In 38 patients harbouring 49 hip prostheses, standardized uptake values (SUV) in 6 periprosthetic regions and the bladder were compared between PET attenuation corrected with either conventional or MAR CT. Results: Using conventional CT, measured activity decreased with 2 to 13% when the prosthesis was inserted. Use of MAR CT increased measured activity by up to 11% compared with conventional CT and reduced the relative difference with the reference values to under 5% in all sources. In all regions, to the exception of the prosthesis shaft, SUV_mean increased significantly (p < 0.001) by use of MAR CT. Median (interquartile range) percentual increases of SUV_mean were 1.4 (0.0–4.2), 4.0 (1.8–7.8), 7.8 (4.1–12.4), 1.5 (0.0–3.2), 1.4 (0.8–2.8) in acetabulum, lateral neck, medial neck, lateral diaphysis and medial diaphysis, respectively. Except for the shaft, the coefficient of variation did not increase significantly. Except for the erratic changes in the prosthesis shaft, decreases in SUV_mean were rare and small. Bladder SUV_mean increased by 0.9% in patients with unilateral prosthesis and by 4.1% in patients with bilateral prosthesis. Conclusions: In a realistic hip prosthesis phantom, Smart MAR restores quantitative accuracy by recovering counts in underestimated sources. In patient studies, Smart MAR increases SUV in all areas surrounding the prosthesis, most markedly in the femoral neck region. This proves that underestimation of activity in the PET image is the most prevalent effect due to metal artefacts in the CT image in patients with hip prostheses. Smart MAR increases SUV in the urinary bladder, indicating effects at a distance from the prosthesis.

Background Metal artefact reduction (MAR) techniques still are in limited use in positron emission tomography / computed tomography (PET/CT). This study aimed to investigate the effect of Smart MAR on quantitative PET analysis in the vicinity of hip prostheses.Material and methods Activities were measured on PET/CT images in 6 sources with 10-fold activity concentration contrast to background, attached to the head, neck and the major trochanter of a human cadaveric femur, and in the same sources in similar locations after a hip prosthesis (titanium cup, ceramic head, chrome-cobalt stem) had been inserted into the femur. Measurements were compared between PET attenuation corrected using either conventional or MAR CT. In 46 patients harbouring 61 hip prostheses, standardized uptake values (SUV) in 6 periprosthetic regions and the bladder, were compared between PET attenuation corrected with either conventional or MAR CT. Results Using conventional CT, measured activity decreased from 2 to 13% when the prosthesis was inserted. Use of MAR CT increased measured activity by up to 11 12% compared with conventional CT and reduced the relative difference with the reference values to under 5% in all sources.In all regions, to the exception of the prosthesis shaft, SUV_mean increased significantly (pmean were 1.9 (0.0-4.5), 3.9 (1.8-7.8), 7.0 (3.4-11.1), 1.7 (0.9-3.7), 1.5 (0.8-3.3) in acetabulum, lateral neck, medial neck, lateral diaphysis and medial diaphysis, respectively. Except for the shaft, the coefficient of variation did not increase significantly. Except for the erratic changes in the prosthesis shaft, decreases of SUV_mean were rare and small. Bladder SUV_mean increased by 1% in patients with unilateral and by 4% in patients with bilateral prosthesis. Conclusions In a realistic hip prosthesis phantom, Smart MAR restores quantitative accuracy by recovering counts in underestimated sources. In patient studies, Smart MAR increases SUV in all areas surrounding the prosthesis, most markedly in the femoral neck region. This proves that underestimation of activity is the most prevalent metal artefact in hip prostheses. Smart MAR increases SUV in the urinary bladder, indicating effects at a distance from the prosthesis.

The utility of PET in septicemia for showing its source and possible metastatic infection has been demonstrated. We describe the diagnosis on PET/CT of a spontaneous corpus cavernosum abscess in a 64-year-old man presenting with Streptococcus constellatus septicemia, in whom the clinical diagnosis had been elusive for 10 days.

Case Report A 52-year-old female patient with a history of rectal carcinoma underwent targeted radiotherapy on right-sided pelvic lymph node metastases (42 Gy in 21 fractions). She later developed local post-radiation retroperitoneal fibrosis with resulting ureteric stenosis. Serial oncological follow ups with 18 F-FDG PET-CT showed a right-sided increased uptake in the obturator internus (Figures 1 and 2, X) and obturator externus muscles, at a significant distance inferiorly to the irradiated zone. This uptake first became visible 22 months after the last radiotherapy session, reached a peak after 25 months (Figure 1), and all but disappeared after 32 months without any further oncologic treatment. It was associated with gradual and permanent muscular volume loss compared to the contralateral side. This volume loss reached a maximum after 37 months (Figure 2). The previous pelvic irradiation suggests that post-irradiation scarring led to injury of the

This paper describes the National Electrical Manufacturers Association (NEMA) system performance of the Discovery MI 3-ring PET/CT (GE Healthcare) installed in Bruges, Belgium. This time-of-flight (TOF) PET camera is based on silicon photomultipliers instead of photomultiplier tubes. The NEMA NU2-2012 standard was used to evaluate spatial resolution, sensitivity, image quality (IQ) and count rate curves of the system. Timing and energy resolution were determined. Full width at half maximum (FWHM) of spatial resolution in radial, tangential and axial direction was 4.69, 4.08 and 4.68 mm at 1 cm; 5.58, 4.64 and 5.83 mm at 10 cm; and 7.53, 5.08 and 5.47 mm at 20 cm from the centre of the field of view (FOV) for the filtered backprojection reconstruction. For non-TOF ordered subset expectation maximization (OSEM) reconstruction without point spread function (PSF) correction, FWHM was 3.87, 3.69 and 4.15 mm at 1 cm; 4.80, 3.81 and 4.87 mm at 10 cm; and 7.38, 4.16 and 3.98 mm at 20 cm. Sensitivity was 7.258 cps/kBq at the centre of the FOV and 7.117 cps/kBq at 10-cm radial offset. Contrast recovery (CR) using the IQ phantom for the TOF OSEM reconstruction without PSF correction was 47.4, 59.3, 67.0 and 77.0% for the 10-, 13-, 17- and 22-mm radioactive spheres and 82.5 and 85.1% for the 28- and 37-mm non-radioactive spheres. Background variability (BV) was 16.4, 12.1, 9.1, 6.6, 5.1 and 3.8% for the 10-, 13-, 17-, 22-, 28- and 37-mm spheres. Lung error was 8.5%. Peak noise equivalent count rate (NECR) was 102.3 kcps at 23.0 kBq/ml with a scatter fraction of 41.2%. Maximum accuracy error was 3.88%. Coincidence timing resolution was 375.6 ps FWHM. Energy resolution was 9.3% FWHM. Q.Clear reconstruction significantly improved CR and reduced BV compared with OSEM. System sensitivity and NECR are lower and IQ phantom’s BV is higher compared with larger axial FOV (AFOV) scanners like the 4-ring discovery MI, as expected from the smaller solid angle of the 3-ring system. The other NEMA performance parameters are all comparable with those of the larger AFOV scanners.

We describe the F-18-FDG PET/CT findings in a rare case of mesenteric panniculitis caused by systemic lupus. A previous CT had raised suspicion of a space-occupying lesion in the left hypochondrium in a context of aspecific constitutional symptoms and inflammatory parameters. The diagnosis of panniculitis was confirmed at laparoscopic biopsy directed by the PET findings. Follow-up F-18-FDG PET/CT after 1 month of corticosteroid therapy showed complete disappearance of the abdominal hypermetabolic foci.

Erythromelalgia is a rare condition characterized by attacks of intensely painful, red and warm feet and/or hands. Symptoms typically are triggered by heat and relieved by cooling of the extremities. Primary cases are due to mutations in the gene for a sodium channel expressed in nociceptive and sympathetic ganglion neurons; secondary causes include blood disorders, infections, drugs, connective tissue diseases, neuropathic diseases, including diabetic neuropathy, and malignancies. We present bone scan findings in a case of erythromelalgia in an 18 years old student, in whom the symptoms developed suddenly. No underlying disease could be demonstrated and the patient fully recovered. The scan findings were strikingly similar to those of reflex sympathetic dystrophy.